As a refrigerator for cooling or freezing a cooling target such as water, a turborefrigerator having a turbocompressor which compressing and discharging a refrigerant by means of rotation of an impeller is known. The turbocompressor installed at this turborefrigerator includes, for instance, as shown in Patent Document 1, a motor installed in a motor casing, an impeller rotated by rotational power of the motor, and a pair of gears transmitting the rotational power of the motor to the impeller. One of the pair of gears is installed on a rotary shaft fixed to the impeller, and the other is installed on an output shaft of the motor.